Local dc mains trialled for saving energy

The potential advantages of a localised dc are two fold. The first is that much modern equipment, including televisions and computers use dc, which they have to derive from ac by rectification, which consumes energy. The second is that many renewable sources of electrical energy produce DC, either directly, as in the case of photovoltaics, or in a dc link, and that in order to make them compatible with an ac mains supply, this dc not only has to be inverted but exactly matched, wave peak to wave peak, with the external ac supply. This both consumes energy and adds cost. The reason the mains is ac is that it allows voltages to be boosted for long distance transmission which reduces the cost of cables and resistance losses, but this is much less important in a small, local area. Professor Raj Aggarwal and Dr Miles Redfern, from the University's Department of Electronic and Electrical Engineering are leading a project that will set up 50 computers in the University library to draw their energy from a specially created local dc network. Dr Redfern explained that: "With the explosion of electronic systems in entertainment, communications and computing, all of which are inherently dc powered, dc supply networks have to be considered as an alternative to ac supplies. The library at Bath has ac systems operating alongside the dc ones, providing us with an invaluable test bed to establish if dc supplies can offer advantages for our current electricity demands." Allan Robinson, Head of Product at RWE npower said: "It is vital as an energy generator/supplier we explore every option that will deliver potentially significant energy savings for our customers. Partnerships such as this are vital for two reasons: first to bring together the overwhelming experience of both parties; and secondly to deliver a robust report that will enable the industry to take the technology forward to explore its potential on a larger scale." The funding for the project has come from a Knowledge Transfer Account Partnership Development Award that has been matched by RWE npower.